Based on N-terminal (amino acid) and C-terminal (base) sequences, OFP appears to be a novel protein. Normally present only in the fetus and placenta, it is re-induced early in carcinogenesis, persists in the tumor and is secreted to circulation. The hypothesis is that OFP is produced in and released from pre-malignant lesions in the rat mammary gland after treatment with 7,12-dimethylbenz(a)anthracene (DMBA). The DMBA-induced model will be used to identify mammary lesions producing OFP, and to correlate rate of production and steady state blood levels as a function of time with various histopathological parameters and tumorigenic potential. In addition to tumorigenesis modulating agents (i.e., retinoid and chorionic gonadotropin) this study will apply specific monoclonal antibodies and cDNA to an ELISA assay, immunolocalization and in situ hybridization. The possible interaction of OFP with the cell membrane (receptors) will be evaluated in rat mammary cell lines. The data from this study are relevant to detection of premalignant lesions, and to monitoring chemical carcinogenesis.